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rice (Datta
er al.,
2001). against Uncinula neruror in grapevine ( Y m a m o t o er ol.,
2000). against B. cinerea in cucumber (Tabei
rr
(11.. 1998; Kishimoto er ol.. 2002) and
against Puccinin coruncrta in chrysanthemum (Takiltw cr
01..
1999) and Itillinn
ryegrass (Takahashi er nl., 2005).
Increased resistance of tomato against fungal pathogens was achieved hy
simultar~eous expression of P-1,3-glucanase and class
I
chitinase (PR-2 and PR-3
family, respectively) of tobacco. Field evaluation of transgenic carrot plants
containing the same genes has shown a high level of resistance against major fungal
pathogens of carrots (Melchers et ul., 1998). The constitutive overexpression of
tobacco class I PR-2 and PR-3 transgenes in potato plants enhanced their resistance
against Phytophthora infeslans (Bachmann
er
ul., 1998). Similar results about the
effectiveness of the co-expression of chitinase and P-13-glucanase in plant disease
resistance was also reported by Kombrink er a l . . (2001). Brussicu nupus transgenic
plants, constitutively expressing a chimeric chitinase gene, display field tolerance to
fungal pathogens (Grison er al., 1996). Overexpression of the cloned rice thaumatin-
like
(PR-5)
gene in transgenic rice plants enhanced the resistance against
R.
solani.
the sheath blight fungus (Datta et 01.. 2001). Overexpression of a pepper basic PR-I
gene in transgenic tobacco plants enhanced resistance to heavy metals and pathogens
(Sarowar et 01.. 2005). A11 these findings encourage the application of PR-protein
genes in genetic engineering technologies for crop improvement.
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